High temperature tungsten metallization process

ABSTRACT

Embodiments of the invention provide an improved process for depositing tungsten-containing materials. In one embodiment, the method for forming a tungsten-containing material on a substrate includes forming an adhesion layer containing titanium nitride on a dielectric layer disposed on a substrate, forming a tungsten nitride intermediate layer on the adhesion layer, wherein the tungsten nitride intermediate layer contains tungsten nitride and carbon. The method further includes forming a tungsten barrier layer (e.g., tungsten or tungsten-carbon material) from the tungsten nitride intermediate layer by thermal decomposition during a thermal annealing process (e.g., temperature from about 700° C. to less than 1,000° C.). Subsequently, the method includes optionally forming a nucleation layer on the tungsten barrier layer, optionally exposing the tungsten barrier layer and/or the nucleation layer to a reducing agent during soak processes, and forming a tungsten bulk layer on or over the tungsten barrier layer and/or the nucleation layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of co-pending U.S. patent applicationSer. No. 13/660,463, filed Oct. 25, 2012, which claims benefit of U.S.provisional patent application Ser. No. 61/553,117, filed Oct. 28, 2011.Each of the aforementioned patent applications is herein incorporated byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the invention relate to the processing of substrates, andmore particularly relate to methods for forming tungsten materials onsubstrates using vapor deposition processes.

2. Description of the Related Art

Semiconductor and electronics processing industries continue to strivefor larger production yields while increasing the uniformity of layersdeposited on substrates having larger surface areas. These same factorsin combination with new materials also provide higher integration ofcircuits per area of the substrate. As circuit integration increases,the need for greater uniformity and process control regarding layerthickness rises. As a result, various technologies have been developedto deposit layers on substrates in a cost-effective manner, whilemaintaining control over the characteristics of the layer.

Therefore, there is a need for an improved process to deposittungsten-containing materials with good uniformity using vapordeposition techniques.

SUMMARY OF THE INVENTION

Embodiments of the invention provide an improved process for depositingtungsten-containing materials. The process utilizes soak processes andvapor deposition process to provide tungsten-containing materials havingsignificantly improved conductivity and surface uniformity, whileincreasing the production level throughput.

In one embodiment, a method for forming a tungsten-containing materialon a substrate includes forming an adhesion layer on a dielectric layer(e.g., silicon or silicon oxide materials) disposed on a substrate,forming a tungsten nitride intermediate layer on the adhesion layer,heating the tungsten nitride intermediate layer to a decompositiontemperature during a thermal annealing process (e.g., RTP). The tungstennitride intermediate layer decomposes to form a tungsten barrier layercontaining metallic tungsten or tungsten-carbon material at adecomposition temperature within a range from about 700° C. to less than1,000° C. The method further includes optionally forming a nucleationlayer on the tungsten barrier layer and forming a tungsten bulk layer onthe nucleation layer. The adhesion layer generally contains a metal or ametal nitride material. In many examples, the adhesion layer containstitanium, titanium nitride, alloys thereof, or combinations thereof. Thetungsten nitride intermediate layer generally contains tungsten,nitrogen, and carbon. In some examples, the tungsten nitrideintermediate layer further contains oxygen.

In another embodiment, the method for forming a tungsten-containingmaterial on a substrate includes forming an adhesion layer containingtitanium nitride on a dielectric layer disposed on a substrate, forminga tungsten nitride intermediate layer on the adhesion layer, wherein thetungsten nitride intermediate layer contains tungsten nitride andcarbon, forming a tungsten barrier layer from the tungsten nitrideintermediate layer during a thermal annealing process, wherein thetungsten barrier layer contains metallic tungsten or tungsten-carbonmaterial formed by thermal decomposition of the tungsten nitrideintermediate layer, optionally forming a nucleation layer on thetungsten barrier layer, and forming a tungsten bulk layer on thenucleation layer.

In another embodiment, the method for forming a tungsten-containingmaterial on a substrate includes heating the tungsten nitrideintermediate layer to a decomposition temperature during a thermalannealing process, wherein the tungsten nitride intermediate layerdecomposes to form a tungsten barrier layer containing metallic tungstenor tungsten-carbon material and the decomposition temperature is withina range from about 700° C. to less than 1,000° C.

In some examples, the method includes optionally omitting or not forminga nucleation layer on the tungsten barrier layer. Instead, the methodincludes optionally exposing the tungsten barrier layer to a reducingagent during a soak process and forming a tungsten bulk layer directlyon the tungsten barrier layer. In one example, the method includesforming a tungsten bulk layer directly on the tungsten barrier layerwithout exposing the tungsten barrier layer to a reducing agent during asoak process.

In another embodiment, the method for forming a tungsten-containingmaterial on a substrate includes exposing the tungsten barrier layer toa reducing agent during a pre-soak process, forming a nucleation layeron the tungsten barrier layer, exposing the nucleation layer to thereducing agent during a post-soak process, and forming a tungsten bulklayer on the nucleation layer. The reducing agent utilized during any ofthe soak processes, such as the pre-soak or post-soak process, generallycontains at least one compound selected from silane, disilane, diborane,hydrogen gas (H₂), plasmas thereof, derivatives thereof, or combinationsthereof.

The adhesion layer generally contains a metal or a metal nitridematerial, such as titanium, titanium nitride, alloys thereof, orcombinations thereof. The adhesion layer has a thickness within a rangefrom about 2 Å to about 100 Å, more narrowly within a range from about 3Å to about 80 Å, more narrowly within a range from about 4 Å to about 50Å, more narrowly within a range from about 5 Å to about 25 Å, morenarrowly within a range from about 5 Å to about 20 Å, more narrowlywithin a range from about 5 Å to about 15 Å, and more narrowly within arange from about 5 Å to about 10 Å. The adhesion layer is generallydeposited by atomic layer deposition (ALD), plasma-enhanced ALD(PE-ALD), or physical vapor deposition (PVD) processes.

The tungsten nitride intermediate layer generally has a thickness withina range from about 5 Å to about 150 Å, more narrowly within a range fromabout 10 Å to about 80 Å, and more narrowly within a range from about 30Å to about 50 Å. The tungsten nitride intermediate layer is generallydeposited by ALD, chemical vapor deposition (CVD), or PVD processes. TheCVD process utilized to deposit or otherwise form tungsten nitrideintermediate layer may include thermal CVD, pulsed-CVD, plasma-enhancedCVD (PE-CVD), or pulsed PE-CVD.

In other examples, the tungsten nitride intermediate layer has atungsten concentration within a range from about 30 at % (atomicpercent) to about 60 at %, a nitrogen concentration within a range fromabout 30 at % to about 60 at %, a carbon concentration within a rangefrom about 3 at % to about 20 at %, and an oxygen concentration within arange from about 0 at % to about 10 at %, more narrowly, a tungstenconcentration within a range from about 35 at % to about 55 at %, anitrogen concentration within a range from about 35 at % to about 55 at%, a carbon concentration within a range from about 5 at % to about 15at %, and an oxygen concentration within a range from about 0 at % toabout 5 at %. However, once the tungsten nitride intermediate layer isthermally decomposed to form the tungsten barrier layer (e.g., RTPexposure), the subsequent tungsten barrier layer has a tungstenconcentration within a range from about 70 at % to about 99.99 at %, anitrogen concentration within a range from about 0 at % to about 10 at%, a carbon concentration within a range from about 0 at % to about 15at %, and an oxygen concentration within a range from about 0 at % toabout 20 at %, more narrowly, a tungsten concentration within a rangefrom about 80 at % to about 99.9 at %, a nitrogen concentration within arange from about 0 at % to about 5 at %, a carbon concentration within arange from about 0 at % to about 10 at %, and an oxygen concentrationwithin a range from about 0 at % to about 15 at %, and more narrowly, atungsten concentration within a range from about 85 at % to about 99.9at %, a nitrogen concentration within a range from about 0 at % to about2 at %, a carbon concentration within a range from about 0 at % to about5 at %, and an oxygen concentration within a range from about 5 at % toabout 10 at %.

In some examples, the tungsten nitride intermediate layer has a tungstenconcentration within a range from about 40 at % to about 60 at %, anitrogen concentration within a range from about 20 at % to about 40 at%, and a carbon concentration within a range from about 5 at % to about15 at %, more narrowly, a tungsten concentration within a range fromabout 45 at % to about 55 at %, a nitrogen concentration within a rangefrom about 25 at % to about 35 at %, and a carbon concentration within arange from about 8 at % to about 12 at %. However, once the tungstennitride intermediate layer is thermally decomposed to form the tungstenbarrier layer, the tungsten concentration of the tungsten barrier layerhas increased relative to the tungsten concentration of thecorresponding tungsten nitride intermediate layer. Also, the nitrogenand/or carbon concentrations are reduced relative to the nitrogen and/orcarbon concentrations of the corresponding tungsten nitride intermediatelayer. The nitrogen and/or carbon atoms are completely removed orsubstantially removed from within the tungsten barrier layer. Thethickness of the tungsten barrier layer is less than the thickness ofthe tungsten nitride intermediate layer. The thickness of the tungstenbarrier layer is within a range from about 50% to about 80% thethickness of the tungsten nitride intermediate layer, more narrowly, ina range from about 55% to about 70% the thickness of the tungstennitride intermediate layer. The tungsten barrier layer has a tungstenconcentration within a range from about 70 at % to about 99 at %, anitrogen concentration within a range from about 1 ppb to about 10 at %,and a carbon concentration within a range from about 1 ppb to about 10at %, more narrowly, a tungsten concentration within a range from about70 at % to about 90 at %, a nitrogen concentration within a range fromabout 1 ppm to about 5 at %, and a carbon concentration within a rangefrom about 1 ppm to about 5 at %. The tungsten barrier layer has anelectrical resistivity of less than 200 Ωμ-cm, such as about 100 Ωμ-cmor less, as measured through the full stack including the tungsten bulklayer.

In other examples, the tungsten nitride intermediate layer has atungsten concentration within a range from about 40 at % to about 60 at%, a nitrogen concentration within a range from about 5 at % to about 20at %, and a carbon concentration within a range from about 20 at % toabout 40 at %, more narrowly, a tungsten concentration within a rangefrom about 45 at % to about 55 at %, a nitrogen concentration within arange from about 8 at % to about 12 at %, and a carbon concentrationwithin a range from about 25 at % to about 35 at %. However, once thetungsten nitride intermediate layer is thermally decomposed to form thetungsten barrier layer, the subsequent tungsten barrier layer has atungsten concentration within a range from about 70 at % to about 99 at%, a nitrogen concentration within a range from about 1 ppb to about 10at %, and a carbon concentration within a range from about 1 at % toabout 15 at %, more narrowly, a tungsten concentration within a rangefrom about 70 at % to about 90 at %, a nitrogen concentration within arange from about 1 ppm to about 5 at %, and a carbon concentrationwithin a range from about 1 at % to about 10 at %.

In additional examples, the tungsten nitride intermediate layer furthercontains oxygen and has an oxygen concentration within a range fromabout 1 at % to about 10 at %. However, once the tungsten nitrideintermediate layer is thermally decomposed and the tungsten barrierlayer is formed, the subsequent tungsten barrier layer may be free ofoxygen or contain oxygen at a concentration of about 1 at % or less,such as about 1 ppm or less, such as about 1 ppb or less. In someexamples, the tungsten barrier layer has an oxygen concentration withina range from about 1 ppb to about 1 at %.

In some examples, a tungsten nitride intermediate layer decomposes toform a tungsten barrier layer containing metallic tungsten ortungsten-carbon material at a decomposition temperature within a rangefrom about 700° C. to less than 1,000° C. However, in other examples,the decomposition temperature of the tungsten nitride intermediate layeris more narrowly within a range from about 800° C. to about 950° C.,more narrowly within a range from about 850° C. to about 925° C., andmore narrowly, in a range from about 875° C. to about 915° C. In someexamples, the tungsten nitride intermediate layer is heated to atemperature within a range from about 875° C. to about 915° C., forexample, about 900° C., for a time period within a range from about 30seconds to about 10 minutes during the thermal annealing process, morenarrowly within a range from about 1 minute to about 5 minutes duringthe thermal annealing process.

In some examples, the tungsten nitride intermediate layer is heated to atemperature within a range from about 750° C. to about 850° C. for atime period within a range from about 10 minutes to about 60 minutesduring the thermal annealing process. In one example, the tungstennitride intermediate layer is heated to a temperature of about 800° C.for a time period within a range from about 20 minutes to about 40minutes during the thermal annealing process.

The nucleation layer generally contains a metal, such as tungsten,cobalt, ruthenium, copper, alloys thereof, derivatives thereof, orcombinations thereof. In many examples, nucleation layer containsmetallic tungsten, tungsten silicide, tungsten boride, alloys thereof,derivatives thereof, or combinations thereof. The nucleation layer isgenerally formed by ALD, PE-ALD, PVD, CVD, PE-CVD, or pulsed-CVD. Thetungsten bulk layer is generally formed by CVD, pulsed-CVD, PE-CVD, orpulsed PE-CVD.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the inventioncan be understood in detail, a more particular description of theinvention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of the invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 illustrates a flow chart depicting a process sequence for forminga tungsten-containing material by processes according to embodimentsdescribed herein.

FIGS. 2A-2G depict cross-sectional views of a workpiece during steps ofthe process illustrated in FIG. 1 and according to embodiments describedherein.

FIGS. 3A-3B depict multi-chamber processing systems according toembodiments described herein.

Appendix A containing 20 pages is attached herein and incorporated byreference in its entirety.

DETAILED DESCRIPTION

Embodiments of the invention provide an improved process for depositingtungsten-containing materials. The process utilizes tungsten containinggas and vapor deposition process to provide tungsten-containingmaterials having significantly improved conductivity and surfaceuniformity, while increasing the production level throughput.

FIG. 1 illustrates an exemplary method or process 100 for forming atungsten-containing material on a substrate, according to embodimentsdescribed herein. In one embodiment, process 100 includes optionallyexposing a dielectric layer disposed on a substrate to a precleanprocess (step 110), forming an adhesion layer on the dielectric layer(step 120), forming a tungsten nitride intermediate layer on theadhesion layer (step 130), forming a tungsten barrier layer from thetungsten nitride intermediate layer during a thermal annealing process,such as an RTP (step 140), optionally exposing the tungsten barrierlayer to a pre-soak process (step 150), optionally forming a nucleationlayer on the tungsten barrier layer (step 160), optionally exposing thenucleation layer to a post-soak process (step 170), and forming atungsten bulk layer over the tungsten barrier layer or the nucleationlayer (step 180).

FIGS. 2A-2G depict exemplary cross-sectional views of workpiece 200 atlapsed process steps after to being processed at different steps of ametallization sequence process, such as steps 110-180 of process 100, asdescribed by some embodiments herein. Process 100 is utilized to formtungsten metallization materials on a substrate surface. In one example,workpieces 200, depicted in FIGS. 2A-2G, may be fabricated or otherwiseformed by process 100.

FIG. 2A depicts workpiece 200 that contains a dielectric layer 210disposed on a substrate 202 and an aperture 208 formed or otherwisecontained within dielectric layer 210. Generally, substrate 202 is asilicon substrate or at least contains silicon or a silicon-basedmaterial. In many examples, workpiece 200 is a semiconductor workpiecehaving a silicon substrate or wafer as substrate 202, dielectric layer210 contains at least one dielectric material, such as silicon,monocrystalline silicon, microcrystalline silicon, polycrystallinesilicon (polysilicon), amorphous silicon, hydrogenated amorphoussilicon, silicon oxide materials, dopant derivatives thereof, orcombinations thereof. Aperture 208 may be vias, trenches, lines, holes,or other apertures utilized in a semiconductor, solar, or otherelectronic devices, such as high aspect contact plugs.

Upper surface 204 of workpiece 200 may have at least one or morecontaminants disposed thereon. Contaminants disposed on upper surface204 of workpiece 200 may include native oxides, residues, particles,and/or other contaminants. Step 110, an optional step, may be utilizedto clean upper surface 204 of workpiece 200, in various embodiments ofprocess 100. Alternatively, step 110 may be excluded in otherembodiments of process 100, which then starts with step 120. Forexample, contaminants are removed from upper surface 204 of workpiece200 during an optional process step, such as a preclean process or abackside polishing process during step 110. FIG. 2A depicts uppersurface 204 of workpiece 200 free of contaminants or substantially freeof contaminants, including free of native oxides.

In some embodiments during step 110, upper surface 204 of workpiece 200may be exposed to a pre-clean process. Upper surface 204 usuallycontains silicon, polysilicon, or silicon containing surface (e.g.,silicide) disposed thereon and may be exposed to pre-clean solution,vapor, or plasma during a pre-clean process. In one embodiment, uppersurface 204 is exposed to a reducing agent in gaseous form, such assilane, disilane, diborane, hydrogen, phosphine, or derivatives thereof.A carrier gas may be co-flowed with the reducing agent. Carrier gasesinclude hydrogen, nitrogen, argon, or combinations thereof. In anotherembodiment, upper surface 204 is exposed to a plasma pre-clean process.The plasma may be generated internal (e.g., in situ plasma) or generatedexternally (e.g., remote plasma system). Upper surface 204 may beexposed to a plasma formed from a gas or a gaseous mixture containingargon, helium, neon, hydrogen, nitrogen, ammonia, silane, disilane,diborane, or mixtures thereof. In several examples, the plasma may beformed from a hydrogen and ammonia mixture, a hydrogen and nitrogenmixture, or a nitrogen and ammonia mixture.

In step 120 of process 100, the method includes forming an adhesionlayer on a dielectric layer disposed on a substrate, as depicted in FIG.2B. In many examples, adhesion layer 220 contains a metal or a metalnitride material, such as titanium, titanium nitride, alloys thereof, orcombinations thereof. Adhesion layer 220 has a thickness within a rangefrom about 2 Å to about 100 Å, more narrowly within a range from about 3Å to about 80 Å, more narrowly within a range from about 4 Å to about 50Å, more narrowly within a range from about 5 Å to about 25 Å, morenarrowly within a range from about 5 Å to about 20 Å, more narrowlywithin a range from about 5 Å to about 15 Å, and more narrowly within arange from about 5 Å to about 10 Å. Adhesion layer 220 is generallydeposited by atomic layer deposition (ALD) or physical vapor deposition(PVD) processes.

In step 130 of process 100, the method includes forming tungsten nitrideintermediate layer 230 on adhesion layer 220, as depicted in FIG. 2C.Tungsten nitride intermediate layer 230 generally contains tungsten,nitrogen, and carbon. For example, tungsten nitride intermediate layer230 may contain tungsten nitride and carbon, such that carbon atoms aredisposed within the lattice of a tungsten nitride material, atungsten-carbon material, or other a tungsten-containing material. Insome examples, tungsten nitride intermediate layer 230 may containtungsten carbide. In other examples, tungsten nitride intermediate layer230 further contains oxygen, such that the tungsten nitride intermediatematerial contains tungsten, nitrogen, carbon, and oxygen.

Tungsten nitride intermediate layer 230 generally has a thickness withina range from about 5 Å to about 150 Å, more narrowly within a range fromabout 10 Å to about 80 Å, and more narrowly within a range from about 30Å to about 50 Å. Tungsten nitride intermediate layer 230 is generallydeposited by ALD, chemical vapor deposition, or PVD. The CVD processutilized to deposit or otherwise form tungsten nitride intermediatelayer may include thermal CVD, pulsed-CVD, plasma-enhanced CVD (PE-CVD),or pulsed PE-CVD.

Vapor deposition processes that may be utilized to deposit or otherwiseform tungsten nitride intermediate layer 230 are described in commonlyassigned U.S. Pat. Nos. 6,607,976, 7,507,660, 7,595,263, 7,732,327, and7,964,505, as well as U.S. Pub. No. 2008-0206987, and further describedin the NPL references ECS Transactions, 3 (15) 147-152 (2007) andApplied Physics Letters, 82(14) 2239-2241 (2003), which are incorporatedherein by reference for disclosure of deposition techniques utilizedwhile depositing or otherwise forming tungsten nitride materials andother tungsten-containing materials.

In step 140 of process 100, the method includes forming tungsten barrierlayer 240 from tungsten nitride intermediate layer 230 during a thermalannealing process, as depicted in FIG. 2D. Tungsten barrier layer 240contains metallic tungsten or tungsten-carbon material formed by thermaldecomposition of tungsten nitride intermediate layer 230. Thetungsten-carbon material contains metallic tungsten having carbon atomswithin the tungsten lattice and in some examples, may have some tungstencarbide. Tungsten barrier layer 240 is formed on and in contact withadhesion layer 220.

In another embodiment, the method for forming tungsten-containingmaterials on a substrate includes heating tungsten nitride intermediatelayer 230 to a decomposition temperature during a thermal annealingprocess (e.g., RTP). Tungsten nitride intermediate layer 230 decomposesto form tungsten barrier layer 240 containing metallic tungsten ortungsten-carbon material at a decomposition temperature within a rangefrom about 700° C. to less than 1,000° C.

In some examples, tungsten nitride intermediate layer 230 decomposes toform tungsten barrier layer 240 containing metallic tungsten ortungsten-carbon material at a decomposition temperature within a rangefrom about 700° C. to less than 1,000° C. However, in other examples,the decomposition temperature of tungsten nitride intermediate layer 230is more narrowly within a range from about 800° C. to about 950° C.,more narrowly within a range from about 850° C. to about 925° C., andmore narrowly, in a range from about 875° C. to about 915° C. In someexamples, tungsten nitride intermediate layer 230 is heated to atemperature within a range from about 875° C. to about 915° C., forexample, about 900° C., for a time period within a range from about 30seconds to about 10 minutes during the thermal annealing process, morenarrowly within a range from about 1 minute to about 5 minutes duringthe thermal annealing process.

In further examples, tungsten nitride intermediate layer 230 is heatedto a temperature within a range from about 750° C. to about 850° C. fora time period within a range from about 10 minutes to about 60 minutesduring the thermal annealing process. In one example, tungsten nitrideintermediate layer 230 is heated to a temperature of about 800° C. for atime period within a range from about 20 minutes to about 40 minutesduring the thermal annealing process.

In some examples, tungsten nitride intermediate layer 230 has a tungstenconcentration within a range from about 40 at % (atomic percent) toabout 60 at %, a nitrogen concentration within a range from about 20 at% to about 40 at %, and a carbon concentration within a range from about5 at % to about 15 at %, more narrowly, a tungsten concentration withina range from about 45 at % to about 55 at %, a nitrogen concentrationwithin a range from about 25 at % to about 35 at %, and a carbonconcentration within a range from about 8 at % to about 12 at %.

In other examples, tungsten nitride intermediate layer 230 has atungsten concentration within a range from about 30 at % to about 60 at%, a nitrogen concentration within a range from about 30 at % to about60 at %, a carbon concentration within a range from about 3 at % toabout 20 at %, and an oxygen concentration within a range from about 0at % to about 10 at %, more narrowly, a tungsten concentration within arange from about 35 at % to about 55 at %, a nitrogen concentrationwithin a range from about 35 at % to about 55 at %, a carbonconcentration within a range from about 5 at % to about 15 at %, and anoxygen concentration within a range from about 0 at % to about 5 at %.

However, once tungsten nitride intermediate layer 230 is thermallydecomposed to form tungsten barrier layer 240 at step 240, the tungstenconcentration of tungsten barrier layer 240 has increased relative tothe tungsten concentration of the corresponding tungsten nitrideintermediate layer. Also, the nitrogen and/or carbon concentrations arereduced relative to the nitrogen and/or carbon concentrations of thecorresponding tungsten nitride intermediate layer. The nitrogen and/orcarbon atoms are completely removed or substantially removed from withintungsten barrier layer 240.

Tungsten barrier layer 240 has a tungsten concentration within a rangefrom about 70 at % to about 99 at %, a nitrogen concentration within arange from about 1 ppb to about 10 at %, and a carbon concentrationwithin a range from about 1 ppb to about 10 at %, more narrowly, atungsten concentration within a range from about 70 at % to about 90 at%, a nitrogen concentration within a range from about 1 ppm to about 5at %, and a carbon concentration within a range from about 1 ppm toabout 5 at %.

In other examples, tungsten nitride intermediate layer 230 has atungsten concentration within a range from about 40 at % to about 60 at%, a nitrogen concentration within a range from about 5 at % to about 20at %, and a carbon concentration within a range from about 20 at % toabout 40 at %, more narrowly, a tungsten concentration within a rangefrom about 45 at % to about 55 at %, a nitrogen concentration within arange from about 8 at % to about 12 at %, and a carbon concentrationwithin a range from about 25 at % to about 35 at %. However, oncetungsten nitride intermediate layer 230 is thermally decomposed to formtungsten barrier layer 240, the subsequent tungsten barrier layer has atungsten concentration within a range from about 70 at % to about 99 at%, a nitrogen concentration within a range from about 1 ppb to about 10at %, and a carbon concentration within a range from about 1 at % toabout 15 at %, more narrowly, a tungsten concentration within a rangefrom about 70 at % to about 90 at %, a nitrogen concentration within arange from about 1 ppm to about 5 at %, and a carbon concentrationwithin a range from about 1 at % to about 10 at %.

In additional examples, tungsten nitride intermediate layer 230 furthercontains oxygen and has an oxygen concentration within a range fromabout 1 at % to about 10 at %. However, once tungsten nitrideintermediate layer 230 is thermally decomposed and tungsten barrierlayer 240 is formed, the subsequent tungsten barrier layer 240 may befree of oxygen or contain oxygen at a concentration of about 1 at % orless, such as about 1 ppm or less, such as about 1 ppb or less. In someexamples, tungsten barrier layer 240 has an oxygen concentration withina range from about 1 ppb to about 1 at %.

In other examples, tungsten barrier layer 240 has a tungstenconcentration within a range from about 70 at % to about 99.99 at %, anitrogen concentration within a range from about 0 at % to about 10 at%, a carbon concentration within a range from about 0 at % to about 15at %, and an oxygen concentration within a range from about 0 at % toabout 20 at %, more narrowly, a tungsten concentration within a rangefrom about 80 at % to about 99.9 at %, a nitrogen concentration within arange from about 0 at % to about 5 at %, a carbon concentration within arange from about 0 at % to about 10 at %, and an oxygen concentrationwithin a range from about 0 at % to about 15 at %, and more narrowly, atungsten concentration within a range from about 85 at % to about 99.9at %, a nitrogen concentration within a range from about 0 at % to about2 at %, a carbon concentration within a range from about 0 at % to about5 at %, and an oxygen concentration within a range from about 5 at % toabout 10 at %.

The thickness of tungsten barrier layer 240 is less than the thicknessof tungsten nitride intermediate layer 230. The thickness of tungstenbarrier layer 240 is within a range from about 50% to about 80% thethickness of tungsten nitride intermediate layer 230, more narrowlywithin a range from about 55% to about 70% the thickness of tungstennitride intermediate layer 230. Tungsten barrier layer 240 has anelectrical resistivity of less than 200 Ωμ-cm, such as about 100 Ωμ-cmor less, as measured through the full stack including tungsten bulklayer 260.

In step 150 of process 100, the method includes optionally exposingtungsten barrier layer 240 to at least one reducing agent during apre-soak process. The reducing agent generally contains at least onecompound selected from silane, disilane, diborane, hydrogen gas (H₂),plasmas thereof, derivatives thereof, or combinations thereof.

In some embodiments during step 150, workpiece 200 may be optionallyexposed to a reducing gas containing a reducing agent and an optionalcarrier gas during the pre-soak process. The pre-soak process isgenerally a thermal process, but may be a plasma process. The reducingagent adsorbs and/or reacts to workpiece 200 containing tungsten barrierlayer 240 to form a treated surface. The treated surface provides aquicker deposition process for a subsequently deposited material. Thereducing agents may include silane compounds, borane compounds,phosphine compounds, ammonia, amine compounds, hydrogen, derivativesthereof, or combinations thereof. Silane compounds include silane,disilane, trisilane, tetrasilane, chlorosilane, dichlorosilane,tetrachlorosilane, hexachlorodisilane, or derivatives thereof, whileborane compounds include borane, diborane, triborane, tetraborane,pentaborane, alkylboranes, such as triethylborane, or derivativesthereof. Some specific reductants include silane, disilane, diborane,hydrogen, derivatives thereof, or combinations thereof. A carrier gasmay be co-flowed with the reducing agent. Carrier gases includehydrogen, nitrogen, argon, helium, or combinations thereof.

The surface of workpiece 200, such as tungsten barrier layer 240, may beexposed to the pre-soak gas or reducing gas during the pre-soak processin step 150 for a time period within a range from about 1 second toabout 90 seconds, more narrowly within a range from about 5 seconds toabout 60 seconds, more narrowly within a range from about 10 seconds toabout 30 seconds, and more narrowly within a range from about 15 secondsto about 20 seconds. Tungsten barrier layer 240 on workpiece 200 may beexposed to a pre-soak gas while workpiece 200 is heated to a temperaturewithin a range from about 100° C. to about 600° C., more narrowly withina range from about 200° C. to about 600° C., more narrowly within arange from about 300° C. to about 500° C., more narrowly within a rangefrom about 350° C. to about 420° C., and narrowly within a range fromabout 375° C. to about 500° C. during the pre-soak process. Theprocessing chamber may have internal pressure within a range from about0.1 Torr to about 150 Torr, more narrowly within a range from about 1Torr to about 100 Torr, more narrowly within a range from about 10 Torrto about 50 Torr, and more narrowly within a range from about 20 Torr toabout 40 Torr. Tungsten barrier layer 240 disposed on or over workpiece200 may be reduced and/or adsorbs the reducing agent to form aconditioned layer for the subsequent nucleation layer.

In step 160 of process 100, the method includes optionally forming anucleation layer 250 on tungsten barrier layer 240, as depicted in FIG.2E. In some examples, the method includes optionally not forming anucleation layer on tungsten barrier layer 240, exposing tungstenbarrier layer 240 to a reducing agent during a soak process, and forminga tungsten bulk layer directly on tungsten barrier layer 240.

Nucleation layer 250 generally contains a metal, such as tungsten,cobalt, ruthenium, copper, alloys thereof, derivatives thereof, orcombinations thereof. In many examples, nucleation layer containsmetallic tungsten, tungsten silicide, tungsten boride, alloys thereof,derivatives thereof, or combinations thereof. Nucleation layer 250 isgenerally formed by ALD, PE-ALD, PVD, thermal CVD, PE-CVD, pulsed-CVD,or pulsed PE-CVD.

Alternatively, in another embodiment described herein, step 160 may beskipped and a tungsten bulk layer 260 is directly deposited or otherwiseformed on tungsten barrier layer 240, with or without a soak process, asdepicted in FIG. 2G. Therefore, the method of process 100 includesoptionally omitting or not forming nucleation layer 250 on tungstenbarrier layer 240. Instead, the method of process 100 providesoptionally exposing tungsten barrier layer 240 to a reducing agentduring a soak process and depositing or otherwise forming tungsten bulklayer 260 directly on tungsten barrier layer 240. In one example, themethod or process 100 includes depositing or otherwise forming tungstenbulk layer 260 directly on tungsten barrier layer 240 without exposingtungsten barrier layer 240 to a reducing agent during a soak process.

In some embodiment during step 160, nucleation layer 250 is deposited onor over tungsten barrier layer 240. For example, nucleation layer 250may be deposited or otherwise formed by a vapor deposition process suchas ALD, CVD, and/or pulsed-CVD. The processing chamber used to depositnucleation layer 250 may be the same processing chamber used in the soakprocesses as described in steps 240 and 260. Nucleation layer 250 maycontain metallic tungsten, tungsten boride, tungsten silicide, othertungsten alloys, derivatives thereof, or combinations thereof.

Nucleation layer 250 typically has a thickness within a range from about2 Å to about 200 Å. In many examples, nucleation layer 250 has athickness within a range from about 2 Å to about 50 Å, more narrowlywithin a range from about 3 Å to about 30 Å, more narrowly within arange from about 4 Å to about 20 Å, and more narrowly within a rangefrom about 5 Å to about 10 Å.

In one example, nucleation layer 250 is deposited or otherwise formed ontungsten barrier layer 240 which is sequentially exposed to tungstenhexafluoride and reducing agent (e.g., silane or diborane) during an ALDprocess. In another example, nucleation layer 250 is deposited orotherwise formed on tungsten barrier layer 240 which is simultaneouslyexposed to tungsten hexafluoride and reducing agent (e.g., silane ordiborane) during a pulsed-CVD process.

In step 170 of process 100, the method includes optionally exposingnucleation layer 250 to a reducing agent during a post-soak process. Thereducing agent may be the same reducing agent utilized in step 150during the pre-soak process or may be a different reducing agent. Thereducing agent contains at least one compound selected from silane,disilane, diborane, hydrogen gas (H₂), plasmas thereof, derivativesthereof, or combinations thereof.

In some embodiments during step 170, workpiece 200 may be optionallyexposed to a reducing gas containing a reducing agent and an optionalcarrier gas during the post-soak process. The post-soak process isgenerally a thermal process, but may be a plasma process. The reducingagent adsorbs and/or reacts to workpiece 200 containing nucleation layer250 or tungsten barrier layer 240 to form a treated surface. The treatedsurface provides a quicker deposition process for a subsequentlydeposited material. The reducing agents may include silane compounds,borane compounds, phosphine compounds, ammonia, amine compounds,hydrogen, derivatives thereof, or combinations thereof. Silane compoundsinclude silane, disilane, trisilane, tetrasilane, chlorosilane,dichlorosilane, tetrachlorosilane, hexachlorodisilane, or derivativesthereof, while borane compounds include borane, diborane, triborane,tetraborane, pentaborane, alkylboranes, such as triethylborane, orderivatives thereof. Some specific reductants include silane, disilane,diborane, hydrogen, derivatives thereof, or combinations thereof. Acarrier gas may be co-flowed with the reducing agent. Carrier gasesinclude hydrogen, nitrogen, argon, helium, or combinations thereof.

The surface of workpiece 200, such as nucleation layer 250 or tungstenbarrier layer 240, may be exposed to the post-soak gas or reducing gasduring the post-soak process in step 170 for a time period within arange from about 1 second to about 90 seconds, more narrowly within arange from about 5 seconds to about 60 seconds, more narrowly within arange from about 10 seconds to about 30 seconds, and more narrowlywithin a range from about 15 seconds to about 20 seconds. Nucleationlayer 250 or tungsten barrier layer 240 disposed on workpiece 200 may beexposed to a post-soak gas while workpiece 200 is heated to atemperature within a range from about 100° C. to about 600° C., morenarrowly within a range from about 200° C. to about 600° C., morenarrowly within a range from about 300° C. to about 500° C., morenarrowly within a range from about 350° C. to about 420° C., andnarrowly within a range from about 375° C. to about 500° C. during thepost-soak process. The processing chamber may have internal pressurewithin a range from about 0.1 Torr to about 150 Torr, more narrowlywithin a range from about 1 Torr to about 100 Torr, more narrowly withina range from about 10 Torr to about 50 Torr, and more narrowly within arange from about 20 Torr to about 40 Torr. Nucleation layer 250 ortungsten barrier layer 240 disposed on or over workpiece 200 may bereduced and/or adsorbs the reducing agent to form a conditioned layerfor the subsequent nucleation layer.

In step 180 of process 100, the method includes forming a tungsten bulklayer 260 on nucleation layer 250, as depicted in FIG. 2F. Generally,the remaining volume of aperture 208 is completely filled with tungstenbulk layer 260 during step 180. Tungsten bulk layer 260 is usually freeof voids or cavities within the buried word/bit-line trench. Tungstenbulk layer 260 is generally formed by thermal CVD, pulsed-CVD, PE-CVD,or pulsed PE-CVD. Alternatively, as described in other embodimentsherein, tungsten bulk layer 260 is directly deposited or otherwiseformed on tungsten barrier layer 240, with or without a soak process, asdepicted in FIG. 2G.

In one embodiment during step 180, tungsten bulk layer 260 may bedeposited on or over nucleation layer 250. Tungsten bulk layer 260 maybe deposited by a vapor deposition process that includes CVD orpulsed-CVD. The processing chamber used to deposit tungsten bulk layer260 may be the same processing chamber used in the post-soak process asdescribed in step 170. Tungsten bulk layer 260 may contain metallictungsten, tungsten alloys, tungsten-containing materials (e.g., tungstenboride, tungsten silicide, or tungsten phosphide), or combinationsthereof.

In one example, tungsten bulk layer 260 may be deposited on or overnucleation layer 250 on workpiece 200 which is simultaneously exposed totungsten hexafluoride and hydrogen gas during a CVD process. In anotherexample, a PVD process utilizing a tungsten source is used to deposittungsten bulk layer 260 on or over nucleation layer 250. Processes forsoaking nucleation layer 250 and depositing tungsten bulk layer 260thereon are further described in the commonly assigned U.S. Pat. No.6,156,382, which is incorporated herein by reference.

In another embodiment described herein, a buried wordline trench or aburied bitline trench is etched into a substrate, such as a siliconsubstrate, and then filled with the tungsten materials as describedherein. Page 20 of Appendix A is entitled “Buried Wordline TrenchStructure” and is incorporated herein by reference in its entirety. Page20 depicts a buried wordline trench or a buried bitline trench etchedinto silicon substrate. An etch stop layer containing silicon nitride orother material may be disposed on the substrate. A trench liner isformed on the surfaces of the trench. In some examples, the trench lineris a dielectric trench liner, such as a layer containing silicon oxide(e.g., thermal silicon oxide). The buried word/bit-line trench generallyhas a depth within a range from about 50 nm to about 500 nm, such asabout 100 nm to about 300 nm, for example, about 180 nm within thesubstrate.

In other embodiments described herein, process 100, including steps120-180, is utilized to form tungsten metallization materials within theburied word/bit-line trench formed within or on the substrate. In oneexample, a workpiece contains an aperture etched or otherwise formedwithin a substrate, such as a silicon substrate. The aperture may be atrench, such as a buried wordline trench or a buried bitline trench,referred herein as a buried word/bit-line trench. The upper surface ofthe substrate may optional contain one or more layers which the apertureor trench is also formed through. In one example, an etch stop layer(e.g., containing silicon nitride) is disposed on the supper surface ofthe substrate and the buried word/bit-line trench is formed through theetch stop layer and into the substrate.

In step 120 of process 100, the method includes forming an adhesionlayer within the buried word/bit-line trench and/or on the dielectrictrench liner formed within the buried word/bit-line trench. The adhesionlayer generally contains a metal or a metal nitride material, such astitanium, titanium nitride, alloys thereof, or combinations thereof. Theadhesion layer has a thickness within a range from about 2 Å to about100 Å, more narrowly within a range from about 3 Å to about 80 Å, morenarrowly within a range from about 4 Å to about 50 Å, more narrowlywithin a range from about 5 Å to about 25 Å, more narrowly within arange from about 5 Å to about 20 Å, more narrowly within a range fromabout 5 Å to about 15 Å, and more narrowly within a range from about 5 Åto about 10 Å. The adhesion layer is generally deposited by ALD or PVDprocesses.

In step 130 of process 100, the method includes forming a tungstennitride intermediate layer on the adhesion layer within the buriedword/bit-line trench. The tungsten nitride intermediate layer generallycontains tungsten, nitrogen, carbon, and oxygen. For example, thetungsten nitride intermediate layer may contain tungsten nitride andcarbon, such that carbon atoms are disposed within the lattice of atungsten nitride material, a tungsten-carbon material, or other atungsten-containing material. In some examples, the tungsten nitrideintermediate layer may contain tungsten carbide. In other examples, thetungsten nitride intermediate layer further contains oxygen, such thatthe tungsten nitride intermediate material contains tungsten, nitrogen,carbon, and oxygen.

The tungsten nitride intermediate layer generally has a thickness withina range from about 5 Å to about 150 Å, more narrowly within a range fromabout 10 Å to about 80 Å, and more narrowly within a range from about 30Å to about 50 Å. The tungsten nitride intermediate layer is generallydeposited by ALD, chemical vapor deposition, or PVD. The CVD processutilized to deposit or otherwise form tungsten nitride intermediatelayer may include thermal CVD, pulsed-CVD, plasma-enhanced CVD (PE-CVD),or pulsed PE-CVD.

In step 140 of process 100, the method includes forming the tungstenbarrier layer from the tungsten nitride intermediate layer within theburied word/bit-line trench during a thermal annealing process, such asan RTP. The tungsten barrier layer contains metallic tungsten ortungsten-carbon material formed by thermal decomposition of the tungstennitride intermediate layer. The tungsten-carbon material containsmetallic tungsten having carbon atoms within the tungsten lattice and insome examples, may have some tungsten carbide. The tungsten barrierlayer is formed on and in contact with the adhesion layer.

In another embodiment, the method for forming tungsten-containingmaterials within the buried word/bit-line trench formed in the substrateincludes heating the tungsten nitride intermediate layer to adecomposition temperature during a thermal annealing process (e.g.,RTP). The tungsten nitride intermediate layer decomposes to form thetungsten barrier layer containing metallic tungsten or tungsten-carbonmaterial at a decomposition temperature within a range from about 700°C. to less than 1,000.

In some examples, the tungsten nitride intermediate layer decomposes toform the tungsten barrier layer containing metallic tungsten ortungsten-carbon material at a decomposition temperature within a rangefrom about 700° C. to less than 1,000° C. However, in other examples,the decomposition temperature of the tungsten nitride intermediate layeris more narrowly within a range from about 800° C. to about 950° C.,more narrowly within a range from about 850° C. to about 925° C., andmore narrowly, in a range from about 875° C. to about 915° C. In someexamples, the tungsten nitride intermediate layer is heated to atemperature within a range from about 875° C. to about 915° C., forexample, about 900° C., for a time period within a range from about 30seconds to about 10 minutes during the thermal annealing process, morenarrowly within a range from about 1 minute to about 5 minutes duringthe thermal annealing process.

In further examples, the tungsten nitride intermediate layer is heatedto a temperature within a range from about 750° C. to about 850° C. fora time period within a range from about 10 minutes to about 60 minuteswhile forming the tungsten barrier layer during the thermal annealingprocess. In one example, the tungsten nitride intermediate layer isheated to a temperature of about 800° C. for a time period within arange from about 20 minutes to about 40 minutes while forming thetungsten barrier layer during the thermal annealing process.

In some examples, the tungsten nitride intermediate layer has a tungstenconcentration within a range from about 30 at % to about 60 at %, anitrogen concentration within a range from about 30 at % to about 60 at%, a carbon concentration within a range from about 3 at % to about 20at %, and an oxygen concentration within a range from about 0 at % toabout 10 at %, more narrowly, a tungsten concentration within a rangefrom about 35 at % to about 55 at %, a nitrogen concentration within arange from about 35 at % to about 55 at %, a carbon concentration withina range from about 5 at % to about 15 at %, and an oxygen concentrationwithin a range from about 0 at % to about 5 at %.

However, once the tungsten nitride intermediate layer is thermallydecomposed to form the tungsten barrier layer at step 240, the tungstenconcentration of the tungsten barrier layer has increased relative tothe tungsten concentration of the corresponding tungsten nitrideintermediate layer. Also, the nitrogen and/or carbon concentrations arereduced relative to the nitrogen and/or carbon concentrations of thecorresponding tungsten nitride intermediate layer. The nitrogen and/orcarbon atoms are completely removed or substantially removed from withinthe tungsten barrier layer.

In some examples, the tungsten barrier layer has a tungstenconcentration within a range from about 70 at % to about 99.99 at %, anitrogen concentration within a range from about 0 at % to about 10 at%, a carbon concentration within a range from about 0 at % to about 15at %, and an oxygen concentration within a range from about 0 at % toabout 20 at %, more narrowly, a tungsten concentration within a rangefrom about 80 at % to about 99.9 at %, a nitrogen concentration within arange from about 0 at % to about 5 at %, a carbon concentration within arange from about 0 at % to about 10 at %, and an oxygen concentrationwithin a range from about 0 at % to about 15 at %, and more narrowly, atungsten concentration within a range from about 85 at % to about 99.9at %, a nitrogen concentration within a range from about 0 at % to about2 at %, a carbon concentration within a range from about 0 at % to about5 at %, and an oxygen concentration within a range from about 5 at % toabout 10 at %.

The thickness of the tungsten barrier layer is less than the thicknessof the tungsten nitride intermediate layer. The thickness of thetungsten barrier layer is within a range from about 50% to about 80% thethickness of the tungsten nitride intermediate layer, more narrowlywithin a range from about 55% to about 70% the thickness of the tungstennitride intermediate layer. The tungsten barrier layer has an electricalresistivity of less than 200 Ωμ-cm, such as about 100 Ωμ-cm or less, asmeasured through the full stack including the tungsten bulk layer.

In step 150 of process 100, the method includes optionally exposing thetungsten barrier layer within the buried word/bit-line trench to atleast one reducing agent during a pre-soak process. The reducing agentgenerally contains at least one compound selected from silane, disilane,diborane, hydrogen gas (H₂), plasmas thereof, derivatives thereof, orcombinations thereof.

In some embodiments during step 150, the workpiece containing the buriedword/bit-line trenches formed within the substrate may be optionallyexposed to a reducing gas containing a reducing agent and an optionalcarrier gas during the pre-soak process. The pre-soak process isgenerally a thermal process, but may be a plasma process. The reducingagent adsorbs and/or reacts to the workpiece containing the tungstenbarrier layer to form a treated surface. The treated surface provides aquicker deposition process for a subsequently deposited material. Thereducing agents may include silane compounds, borane compounds,phosphine compounds, ammonia, amine compounds, hydrogen, derivativesthereof, or combinations thereof. Silane compounds include silane,disilane, trisilane, tetrasilane, chlorosilane, dichlorosilane,tetrachlorosilane, hexachlorodisilane, or derivatives thereof, whileborane compounds include borane, diborane, triborane, tetraborane,pentaborane, alkylboranes, such as triethylborane, or derivativesthereof. Some specific reductants include silane, disilane, diborane,hydrogen, derivatives thereof, or combinations thereof. A carrier gasmay be co-flowed with the reducing agent. Carrier gases includehydrogen, nitrogen, argon, helium, or combinations thereof.

The surface of the workpiece, such as the tungsten barrier layer withinthe buried word/bit-line trench, may be exposed to the pre-soak gas orreducing gas during the pre-soak process in step 150 for a time periodwithin a range from about 1 second to about 90 seconds, more narrowlywithin a range from about 5 seconds to about 60 seconds, more narrowlywithin a range from about 10 seconds to about 30 seconds, and morenarrowly within a range from about 15 seconds to about 20 seconds. Thetungsten barrier layer on the workpiece may be exposed to a pre-soak gaswhile the workpiece is heated to a temperature within a range from about100° C. to about 600° C., more narrowly within a range from about 200°C. to about 600° C., more narrowly within a range from about 300° C. toabout 500° C., more narrowly within a range from about 350° C. to about420° C., and narrowly within a range from about 375° C. to about 500° C.during the pre-soak process. The processing chamber may have internalpressure within a range from about 0.1 Torr to about 150 Torr, morenarrowly within a range from about 1 Torr to about 100 Torr, morenarrowly within a range from about 10 Torr to about 50 Torr, and morenarrowly within a range from about 20 Torr to about 40 Torr. Thetungsten barrier layer disposed on or over the workpiece may be reducedand/or adsorbs the reducing agent to form a conditioned layer for thesubsequent nucleation layer.

In step 160 of process 100, the method includes optionally forming a thenucleation layer on the tungsten barrier layer within the buriedword/bit-line trench. In some examples, the method includes optionallynot forming a nucleation layer on the tungsten barrier layer, exposingthe tungsten barrier layer to a reducing agent during a soak process,and forming a tungsten bulk layer directly on the tungsten barrier layerwithin the buried word/bit-line trench.

The nucleation layer generally contains a metal, such as tungsten,cobalt, ruthenium, copper, alloys thereof, derivatives thereof, orcombinations thereof. In many examples, nucleation layer containsmetallic tungsten, tungsten silicide, tungsten boride, alloys thereof,derivatives thereof, or combinations thereof. The nucleation layer isgenerally formed by ALD, PE-ALD, PVD, thermal CVD, PE-CVD, pulsed-CVD,or pulsed PE-CVD.

Alternatively, in another embodiment described herein, step 160 may beskipped and a the tungsten bulk layer is directly deposited or otherwiseformed on the tungsten barrier layer, with or without a soak process,within the buried word/bit-line trench. Therefore, the method of process100 includes optionally omitting or not forming the nucleation layer onthe tungsten barrier layer within the buried word/bit-line trench.Instead, the method of process 100 provides optionally exposing thetungsten barrier layer to a reducing agent during a soak process anddepositing or otherwise forming the tungsten bulk layer directly on thetungsten barrier layer within the buried word/bit-line trench. In oneexample, the method or process 100 includes depositing or otherwiseforming the tungsten bulk layer directly on the tungsten barrier layerwithin the buried word/bit-line trench without exposing the tungstenbarrier layer to a reducing agent during a soak process.

In some embodiment during step 160, the nucleation layer is deposited onor over the tungsten barrier layer within the buried word/bit-linetrench. For example, the nucleation layer may be deposited or otherwiseformed by a vapor deposition process such as ALD, CVD, and/orpulsed-CVD. The processing chamber used to deposit the nucleation layermay be the same processing chamber used in the soak processes asdescribed in steps 240 and 260. The nucleation layer may containmetallic tungsten, tungsten boride, tungsten silicide, other tungstenalloys, derivatives thereof, or combinations thereof.

The nucleation layer typically has a thickness within a range from about2 Å to about 200 Å. In many examples, the nucleation layer has athickness within a range from about 2 Å to about 50 Å, more narrowlywithin a range from about 3 Å to about 30 Å, more narrowly within arange from about 4 Å to about 20 Å, and more narrowly within a rangefrom about 5 Å to about 10 Å.

In one example, the nucleation layer is deposited or otherwise formed onthe tungsten barrier layer within the buried word/bit-line trench andthe tungsten barrier layer is sequentially exposed to tungstenhexafluoride and reducing agent (e.g., silane or diborane) during an ALDprocess. In another example, the nucleation layer is deposited orotherwise formed on the tungsten barrier layer which is simultaneouslyexposed to tungsten hexafluoride and reducing agent (e.g., silane ordiborane) during a pulsed-CVD process.

In step 170 of process 100, the method includes optionally exposing thenucleation layer within the buried word/bit-line trench to a reducingagent during a post-soak process. The reducing agent may be the samereducing agent utilized in step 150 during the pre-soak process or maybe a different reducing agent. The reducing agent contains at least onecompound selected from silane, disilane, diborane, hydrogen gas (H₂),plasmas thereof, derivatives thereof, or combinations thereof.

In some embodiments during step 170, the workpiece having within theburied word/bit-line trench, may be optionally exposed to a reducing gascontaining a reducing agent and an optional carrier gas during thepost-soak process. The post-soak process is generally a thermal process,but may be a plasma process. The reducing agent adsorbs and/or reacts tothe workpiece containing the nucleation layer or the tungsten barrierlayer to form a treated surface within the buried word/bit-line trench.The treated surface provides a quicker deposition process for asubsequently deposited material. The reducing agents may include silanecompounds, borane compounds, phosphine compounds, ammonia, aminecompounds, hydrogen, derivatives thereof, or combinations thereof.Silane compounds include silane, disilane, trisilane, tetrasilane,chlorosilane, dichlorosilane, tetrachlorosilane, hexachlorodisilane, orderivatives thereof, while borane compounds include borane, diborane,triborane, tetraborane, pentaborane, alkylboranes, such astriethylborane, or derivatives thereof. Some specific reductants includesilane, disilane, diborane, hydrogen, derivatives thereof, orcombinations thereof. A carrier gas may be co-flowed with the reducingagent. Carrier gases include hydrogen, nitrogen, argon, helium, orcombinations thereof.

The surface of the workpiece, such as the nucleation layer or thetungsten barrier layer within the buried word/bit-line trench, may beexposed to the post-soak gas or reducing gas during the post-soakprocess in step 170 for a time period within a range from about 1 secondto about 90 seconds, more narrowly within a range from about 5 secondsto about 60 seconds, more narrowly within a range from about 10 secondsto about 30 seconds, and more narrowly within a range from about 15seconds to about 20 seconds. The nucleation layer or the tungstenbarrier layer disposed on the workpiece may be exposed to a post-soakgas while the workpiece is heated to a temperature within a range fromabout 100° C. to about 600° C., more narrowly within a range from about200° C. to about 600° C., more narrowly within a range from about 300°C. to about 500° C., more narrowly within a range from about 350° C. toabout 420° C., and narrowly within a range from about 375° C. to about500° C. during the post-soak process. The processing chamber may haveinternal pressure within a range from about 0.1 Torr to about 150 Torr,more narrowly within a range from about 1 Torr to about 100 Torr, morenarrowly within a range from about 10 Torr to about 50 Torr, and morenarrowly within a range from about 20 Torr to about 40 Torr. Thenucleation layer or the tungsten barrier layer disposed on or over theworkpiece may be reduced and/or adsorbs the reducing agent to form aconditioned layer for the subsequent nucleation layer.

In step 180 of process 100, the method includes forming a tungsten bulklayer on the nucleation layer within the buried word/bit-line trench.Generally, the remaining volume of the buried word/bit-line trench iscompletely filled with the tungsten bulk layer during step 180. Thetungsten bulk layer is usually free of voids or cavities within theburied word/bit-line trench. The tungsten bulk layer is generally formedby thermal CVD, pulsed-CVD, PE-CVD, or pulsed PE-CVD. Alternatively, asdescribed in other embodiments herein, the tungsten bulk layer isdirectly deposited or otherwise formed (with or without a soak process)on the tungsten barrier layer within the buried word/bit-line trench.

In one embodiment during step 180, the tungsten bulk layer may bedeposited on or over the nucleation layer within the buriedword/bit-line trench. The tungsten bulk layer may be deposited by avapor deposition process that includes CVD or pulsed-CVD. The processingchamber used to deposit the tungsten bulk layer may be the sameprocessing chamber used in the post-soak process as described in step170. The tungsten bulk layer may contain metallic tungsten, tungstenalloys, tungsten-containing materials (e.g., tungsten boride, tungstensilicide, or tungsten phosphide), or combinations thereof.

In one example, the tungsten bulk layer may be deposited on or over thenucleation layer within the buried word/bit-line trench in the substrateof the workpiece which is simultaneously exposed to tungstenhexafluoride and hydrogen gas during a CVD process. In another example,a PVD process utilizing a tungsten source is used to deposit thetungsten bulk layer on or over the nucleation layer within the buriedword/bit-line trench.

A vapor deposition processing chamber used during embodiments describedherein is available from Applied Materials, Inc., located in SantaClara, Calif. Software routines are executed to initiate process recipesor sequences. The software routines, when executed, transform thegeneral purpose computer into a specific process computer that controlsthe chamber operation so that a chamber process is performed during thedeposition process. For example, software routines may be used toprecisely control the activation of the electronic control valves forthe execution of process sequences according to pulsed-CVD and ALDprocesses described by embodiments herein. Alternatively, the softwareroutines may be performed in hardware, as an application specificintegrated circuit or other types of hardware implementation, or acombination of software or hardware.

Process Integration

A tungsten-containing layer and barrier layer as described above hasshown particular utility when integrated with traditional nucleationfill techniques to form features with excellent film properties. Anintegration scheme can include ALD, CVD, pulsed-CVD processes,plasma-enhanced CVD, or pulsed PE-CVD, to deposit tungsten-containinglayers and barrier layers while a nucleation layer may be deposited byALD process. Integrated processing systems capable of performing such anintegration scheme include ENDURA®, ENDURA SL®, CENTURA®, or PRODUCER®processing systems, each available from Applied Materials, Inc., locatedin Santa Clara, Calif. Any of these systems may be configured to includeat least one ALD chamber for depositing the tungsten-containing layerand barrier layer, at least one ALD or pulsed-CVD chamber for depositingthe nucleation layer, at least one CVD chamber for depositing bulk fill,and/or at least one PVD chamber for additional materials. In oneembodiment, one ALD or CVD chamber may be configured to perform allvapor deposition processes related to the tungsten-containing layers.

FIG. 3A depicts a schematic top-view diagram of an exemplarymulti-chamber processing system 300. A similar multi-chamber processingsystem is disclosed in commonly assigned U.S. Pat. No. 5,186,718, whichis incorporated by reference herein. Processing system 300 generallyincludes load lock chambers 302 and 304 for the transfer of substratesinto and out from processing system 300. Typically, since processingsystem 300 is under vacuum, load lock chambers 302 and 304 may “pumpdown” the substrates introduced into processing system 300. First robot310 may transfer the substrates between load lock chambers 302 and 304,and a first set of one or more substrate processing chambers 312, 314,316, and 318 (four are shown). Each processing chamber 312, 314, 316,and 318, may be outfitted to perform a number of substrate processingoperations such as ALD, CVD, PVD, etch, pre-clean, de-gas, orientation,or other substrate processes. First robot 310 also transfers substratesto/from one or more transfer chambers 322 and 324.

Transfer chambers 322 and 324 are used to maintain ultra-high vacuumconditions while allowing substrates to be transferred within processingsystem 300. Second robot 330 may transfer the substrates betweentransfer chambers 322 and 324 and a second set of one or more processingchambers 332, 334, 336, and 338. Similar to processing chambers 312,314, 316, and 318, processing chambers 332, 334, 336, and 338 may beoutfitted to perform a variety of substrate processing operations, suchas ALD, CVD, PVD, etch, pre-clean, de-gas, or orientation. Any ofprocessing chambers 312, 314, 316, 318, 332, 334, 336, and 338 may beremoved from processing system 300 if not necessary for a particularprocess to be performed by processing system 300. Microprocessorcontroller 320 may be used to operate all aspects of processing system300.

In one arrangement, each processing chamber 332 and 338 may be an ALDchamber or other vapor deposition chamber adapted to deposit sequentiallayers containing different chemical compound. For example, thesequential layers may include a layer, a barrier layer, and a nucleationlayer. Processing chambers 334 and 336 may be an ALD chamber, a CVDchamber, or a PVD adapted to form a bulk layer. Processing chambers 312and 314 may be a PVD chamber, a CVD chamber, or an ALD chamber adaptedto deposit a dielectric layer. Also, processing chambers 316 and 318 maybe an etch chamber outfitted to etch apertures or openings forinterconnect features. This one particular arrangement of processingsystem 300 is provided to illustrate some embodiments of the inventionand should not be used to limit the scope of other embodiments of theinvention.

In another integration scheme, one or more ALD chambers are integratedonto a first processing system while one or more bulk layer depositionchambers are integrated onto a second processing system. In thisconfiguration, substrates are first processed in the first system wherea layer, a barrier layer and a nucleation layer is deposited on asubstrate sequentially. Thereafter, the substrates are moved to thesecond processing system where bulk deposition occurs.

In yet another integrated system, a system may include nucleationdeposition as well as bulk fill deposition in a single chamber. Achamber configured to operate in both an ALD mode as well as aconventional CVD mode may be used in processes described herein. Oneexample of such a chamber is described in commonly assigned U.S. Pat.No. 6,878,206, which is incorporated herein by reference.

FIG. 3B depicts a multi-chamber processing system 350 that generallyincludes load lock chambers 352, 354 for the transfer of substrates intoand out from processing system 350. Typically, since processing system350 is under vacuum, load lock chambers 352, 354 may “pump down” thesubstrates introduced into processing system 350. Robot 360 may transferthe substrates between load lock chambers 352, 354, and processingchambers 364, 366, 368, 370, and 372. Each processing chamber 364, 366,368, 370, and 372 may be outfitted to perform a number of substrateprocessing operations such as ALD, CVD, PVD, etch, pre-clean, de-gas,heat, orientation and other substrate processes. Robot 360 alsotransfers substrates to/from transfer chamber 356. Any of processingchambers 364, 366, 368, 370, and 372 may be removed from processingsystem 350 if not necessary for a particular process to be performed byprocessing system 350. Microprocessor controller 380 may be used tooperate all aspects of processing system 350.

In one arrangement, each processing chamber 364 and 370 may be an ALDchamber adapted to deposit a nucleation layer, each processing chamber366 and 368 may be an ALD chamber, a CVD chamber or a PVD chamberadapted to form a bulk fill deposition layer.

In another arrangement, the aforementioned sequential layers may all bedeposited in each of processing chamber 364, 366, 368, 370, and 372 aseach chamber may be outfitted to perform a number of substrateprocessing operations such as ALD, CVD, PVD, etch, pre-clean, de-gas,heat, orientation and other substrate processes. The sequential layersmay include a layer, a barrier layer, a nucleation layer, and a bulklayer. The different arrangement of processing system 350 mentioned hereis provided to illustrate the invention and should not be used to limitthe scope of the embodiments herein.

“Substrate surface” or “substrate”—as used herein—refers to anysubstrate or material surface formed on a substrate upon which filmprocessing is performed during a fabrication process. For example, asubstrate surface on which processing may be performed include materialssuch as silicon, monocrystalline silicon, microcrystalline silicon,polycrystalline silicon (polysilicon), amorphous silicon, hydrogenatedamorphous silicon, strained silicon, silicon on insulator (SOI), dopedsilicon, silicon germanium, germanium, gallium arsenide, glass,sapphire, silicon oxide, silicon nitride, silicon oxynitride, carbondoped silicon oxides, for example, BLACK DIAMOND® low-k dielectric,available from Applied Materials, Inc., located in Santa Clara, Calif.,as well as doped variants thereof, derivatives thereof, and/orcombinations thereof. Substrates may have various dimensions, such as200 mm or 300 mm diameter wafers, as well as, rectangular or squarepanes, such as maybe used for LCDs or solar panel processing. Unlessotherwise noted, embodiments and examples described herein may beconducted on substrates with a 200 mm diameter or a 300 mm diameter.Embodiments of the processes described herein may be used to depositmetallic tungsten, tungsten nitride, tungsten carbide, tungsten-carbonmaterial, tungsten boride, tungsten boride nitride, tungsten silicide,tungsten silicide nitride, tungsten phosphide, derivatives thereof,alloys thereof, combinations thereof, or other tungsten-containingmaterials on many substrates and surfaces, such as adhesion layers(e.g., titanium nitride), or other conductive material layers.Substrates on which embodiments of the invention may be useful include,but are not limited to semiconductor wafers, such as crystalline silicon(e.g., Si<100> or Si<111>), silicon oxide, strained silicon, silicongermanium, doped or undoped polysilicon, doped or undoped siliconwafers, and patterned or non-patterned wafers. Substrates may be exposedto a pretreatment process to polish, etch, reduce, oxidize, hydroxylate,anneal, and/or bake the substrate surface.

“Atomic layer deposition” or “cyclical deposition”—as used herein—refersto the sequential introduction of two or more reactive compounds todeposit a layer of material on a substrate surface. The two, three ormore reactive compounds may alternatively be introduced into a reactionzone of a processing chamber. Usually, each reactive compound isseparated by a time delay to allow each compound to adhere and/or reacton the substrate surface. In one aspect, a first precursor or compound Ais pulsed into the reaction zone followed by a first time delay. Next, asecond precursor or compound B is pulsed into the reaction zone followedby a second delay. During each time delay a purge gas, such as argon ornitrogen, is introduced into the processing chamber to purge thereaction zone or otherwise remove any residual reactive compound orby-products from the reaction zone. Alternatively, the purge gas mayflow continuously throughout the deposition process so that only thepurge gas flows during the time delay between pulses of reactivecompounds. In alternative embodiments, the purge gas may also be areducing agent, such as hydrogen, diborane, or silane. The reactivecompounds are alternatively pulsed until a desired film or filmthickness is formed on the substrate surface. In either scenario, theALD process of pulsing compound A, purge gas, pulsing compound B andpurge gas is an ALD cycle. A cycle can start with either compound A orcompound B and continue the respective order of the cycle untilachieving a film with the desired thickness. In another embodiment, afirst precursor containing compound A, a second precursor containingcompound B, and a third precursor containing compound C are eachseparately and alternatively pulsed into the processing chamber.Alternatively, a first precursor containing compound A and a secondprecursor containing compound B are each separately and alternativelypulsed into the processing chamber while, and a third precursorcontaining compound C is continuously flowed into the processingchamber. Alternatively, a pulse of a first precursor may overlap in timewith a pulse of a second precursor while a pulse of a third precursordoes not overlap in time with either pulse of the first and secondprecursors.

A “pulse”—as used herein—is intended to refer to a quantity of aparticular compound that is intermittently or non-continuouslyintroduced into a reaction zone of a processing chamber. The quantity ofa particular compound within each pulse may vary over time, depending onthe duration of the pulse. The duration of each pulse is variabledepending upon a number of factors such as, for example, the volumecapacity of the processing chamber employed, the vacuum system coupledthereto, and the volatility/reactivity of the particular compounditself. A “half-reaction” as used herein to refer to a pulse of aprecursor followed by a purge step.

Additional Disclosure

CVD tungsten has been used for more than 20 years as a primary conductorfor high aspect ratio contacts, vias, trenches, and lines. Due to thegrowth kinetics of tungsten from WF₆—H₂ it has been possible to fillhigh aspect ratio features with almost 100% step coverage, butsuccessful tungsten metallization utilizes or at least benefits a goodbarrier to protect the underlying dielectric from fluorine, a goodadhesion layer that adheres to both the dielectric and tungsten, andfinally a metallic tungsten nucleation layer to catalyze the WF₆—H₂ CVDreaction.

For high temperature conductor applications such as buried wordline orburied bitline in DRAM devices, the metal conductor must survivesubsequent thermal processing typically greater than 1,000° C. whilemaintaining low resistivity in very narrow lines. In the 20 nmtechnology node these lines are expected to be less than 20 nm in widthand projected to become even narrower in the future. In one examples, abarrier/adhesion/nucleation/fill metallization scheme based on titaniumnitride, ALD tungsten nucleation and CVD tungsten would consume most ofthis feature with relatively high resistivity titanium nitride (greaterthan about 80 Ωμ-cm, such as greater than about 120 Ωμ-cm for thinfilms) and ALD tungsten nucleation (greater than about 100 Ωμ-cm forthickness within a range from about 20 Å to about 40 Å), a new approachis sought.

Embodiments of the invention provide a combination of ultra thintitanium nitride (thickness of about 20 Å or less, for example, about 10Å or less) as an adhesion enhancement, MOCVD WN or W as a fluorine freebarrier layer, and an intermediate RTP step to covert the MOCVD WN or Wto largely pure metallic W. The resulting composite film is wellanchored to dielectric substrates, highly dense, and relatively low inresistivity (less than about 100 Ωμ-cm at about 100 Å film thickness).Embodiments of the methods further provide an optimized ALD tungstennucleation layer be deposited after the intermediate RTP in conjunctionwith CVD-W from WF₆—H₂. The ALD nucleation is an optional step intendedto assure excellent nucleation and feature fill during CVD-W depositionand also to help template low resistivity CVD tungsten growth in thetrench.

Embodiments for tungsten metallization provide: 1. an adhesion layer, 2.a diffusion barrier layer, 3. a tungsten nucleation layer, and 4. a bulkfill of W-CVD from WF₆—H₂.

In typical applications CVD or ALD titanium nitride is used as both anadhesion layer and a diffusion barrier. While a few monolayers (e.g.,about 3 Å to about 10 Å) of titanium nitride can function effectively asan adhesion layer, it typically utilizes tens of angstroms (e.g., about15 Å to about 40 Å) of titanium nitride to make an effective barrieragainst fluorine or boron diffusion. This creates a significant penaltyfor resistance in ultra-narrow features such as DRAM buried wordline orburied bitline applications with total feature critical dimensions ofabout 200 Å or less, such as about 100 Å or less.

While all the functional specifications for tungsten metallization aremaintained, we propose to use novel materials and novel processintegration sequences to reduce the overall resistance of thin tungstenfeatures without compromising on adhesion, diffusion barrierperformance, or tungsten nucleation and fill.

Some of the embodiments of the process sequence for tungstenmetallization described herein include:

1. An adhesion layer of about 20 Å or less of titanium nitride and/orabout 10 Å or less of titanium nitride. The titanium nitride must bethick enough to provide adequate adhesion to the dielectric but need notfunction as a diffusion barrier.

2. A tungsten nitride intermediate layer (e.g., W_(x)N_(y)C_(z) barrierlayer—tungsten nitride intermediate layer 230). This layer is may bedeposited or otherwise formed by a CVD process or an ALD process, suchas by a metallic-organic CVD process or a metallic-organic ALD process.The final film is rich in W with either a WN_(x) or WC_(x) structure.Oxygen may also contain part of the film, but at a low oxygen content.Hydrocarbons and amines may also be present in the film in trace or evensubstantial quantities.

3. An intermediate rapid thermal processing step (RTP) in which atungsten nitride intermediate layer is reduced to a predominantly atungsten barrier layer containing metallic tungsten (e.g., W) ortungsten-carbon material (e.g., WC_(x)) film with the majority of otherelements being outgassed. In the case of metallic-organic WN_(x) theintermediate RTP is intended to reduce the as-deposited WN_(x) to W bythermal decomposition. WN is generally unstable above 800° C. andreverts readily to tungsten. The intermediate RTP may be performed in ahydrogen-rich ambient to facilitate the formation of metallic W and alsoto help volatilize residual hydrocarbons or amines in the as-depositedtungsten nitride intermediate layer. The final form of theTiN/W(x)N(y)C(z) bi-layer after RTP is a smooth, dense, and conformallayer of metallic tungsten or tungsten-carbon material with a thininterfacial layer of titanium nitride to bond it to its underlyingdielectric.

4. A tungsten nucleation and bulk fill process to fill the feature withlow resistivity tungsten. Exemplary implementations of the tungstenmetallization processes may be performed by direct WF₆—H₂ nucleation onthe pre-formed metallic W from the intermediate RTP process. In caseswhere the tungsten layer formed by intermediate RTP of MO-WN_(x) or MO-Wor MO-WC_(x) has an insufficiently metallic surface for effective Wnucleation by WF₆—H₂, it may also be necessary to add a thin (thicknessof about 25 Å or less, such as about 10 Å or less) layer of tungstennucleation deposited by ALD or CVD. This ALD-W nucleation layer may beformed from a reducing agent (e.g., WF₆—SiH₄, WF₆—Si₂H₆, WF₆—B₂H₆), orany comparable reducing agents. The nucleation process may be enhancedby the presence of adsorbed BH_(x) or SiH_(x) layers produced byexposing the surface to a reducing agent, such as diborane, silane,disilane, derivatives thereof, combinations thereof, or other relatedcompounds and may also be performed in the presence of hydrogen gas (H₂)as a minority or majority gas species.

One benefit provided by this scheme is the use of metallic-organic WN(x)or WC(x) CVD processes to form the tungsten nitride intermediate layeras a primary barrier on the titanium nitride adhesion layer. Thisbarrier is then converted to low-resistivity metallic tungsten ortungsten-carbon material after intermediate RTP. The resulting metallictungsten or tungsten-carbon material layer is also expected to possessdensity close to the bulk density of metallic tungsten ortungsten-carbon material. The resistivity of this barrier is far lowerthan the ultimate resistivity of titanium nitride (about 70 Ωμ-cm orgreater, which typically utilizes greater than 100 Å to achieve).

In addition to low resistivity, the post-RTP metallic tungsten ortungsten-carbon material layer provides a metallic or near metallic Winterface for subsequent W growth from WF₆—H₂. In cases where thesurface quality is not fully optimized for WF₆—H₂ nucleation, anoptional ALD-W nucleation layer from WF₆—SiH₄ or WF₆—B₂H₆ or similarreducing agents may be employed, but the layer thickness issignificantly less than for ALD-W nucleation directly on titaniumnitride since the surface after RTP is already very close to metallictungsten.

Yet another benefit by utilizing the metallic-organic WN(x) or WC(x) CVDprocesses to form the tungsten nitride intermediate layer+intermediateRTP is that the resulting metallic tungsten or tungsten-carbon materiallayer is largely dense W, which is a highly effective barrier tofluorine diffusion. Fluorine diffusion is a primary failure mode fortungsten adhesion and gate dielectric damage. Metallic tungsten and or atungsten-containing compound is generally a better and lower resistivitybarrier material for fluorine diffusion than titanium nitride.

In some embodiments described herein, a tungsten pulsed PE-CVD processmay be utilized to form a tungsten nitride intermediate layer (e.g.,tungsten nitride intermediate layer 230). The tungsten pulsed PE-CVDprocess may include 1. a reducing agent dose (e.g., SiH₄, B₂H₆, oranother reducing agent), 2. a gas purge step to remove reducing agentfrom the gas stream, 3. a low-energy RF plasma step to remove adsorbedreducing agent from the surface of the wafer and any areas shadowed byreentrant feature geometry, barrier defect crack's-crevices, or areasdeep in a high aspect ratio feature, 4. a dose of WF₆ to react on thewafer surface with remaining adsorbed reducing agent from the precedingstep, and 5. a gas purge to remove WF₆ and reaction products from thegas stream.

The low energy plasma step above should have ion energies below thesputter threshold of the barrier layer, tungsten, or any exposedsubstrate. It should also be high enough to remove adsorbed reducingagent species, for example, within a range from about 10 eV to about 20eV ion energies—that may be appropriate for this purpose, but other ionenergies may also be effective.

To avoid barrier attack by WF₆, it may be desirable to run one or moreconventional ALD-W cycles prior to starting ALD-W with surface reducingagent removal. In this way the surface of the barrier may be protectedfrom fluorine by a few monolayers of ALD tungsten.

ALD-W with surface reducing agent removal may be run one or more timesas needed to deposit, grow, or otherwise form tungsten in re-entrantareas or deeply recessed areas of semiconductor devices. In general, onewould continue running ALD with reducing agent surface removal until thefeature profile was no longer re-entrant. Once the feature is no longerre-entrant, conformal CVD-W can be used to complete metal fill of thefeature with no internal voids.

While the foregoing is directed to embodiments of the invention, otherand further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

The invention claimed is:
 1. A method for forming a tungsten-containingmaterial on a substrate, comprising: forming an adhesion layer on adielectric layer disposed on a substrate; forming a tungsten nitrideintermediate layer on the adhesion layer, wherein the tungsten nitrideintermediate layer comprises tungsten nitride and carbon; forming atungsten barrier layer from the tungsten nitride intermediate layerduring a thermal annealing process, wherein the tungsten barrier layercomprises metallic tungsten or tungsten-carbon material formed bythermal decomposition of the tungsten nitride intermediate layer;forming a nucleation layer on the tungsten barrier layer; and forming atungsten bulk layer on the nucleation layer.
 2. The method of claim 1,wherein the adhesion layer comprises a metal.
 3. The method of claim 1,wherein the adhesion layer comprises a metal nitride.
 4. A method forforming a tungsten-containing material on a substrate, comprising:forming an adhesion layer on a dielectric layer disposed on a substrate;forming a tungsten nitride intermediate layer on the adhesion layer,wherein the tungsten nitride intermediate layer comprises tungstennitride and carbon; heating the tungsten nitride intermediate layer to adecomposition temperature during a thermal annealing process, whereinthe tungsten nitride intermediate layer decomposes to form a tungstenbarrier layer comprising metallic tungsten or tungsten-carbon materialand the decomposition temperature is within a range from about 700° C.to less than 1,000° C.; forming a nucleation layer on the tungstenbarrier layer; and forming a tungsten bulk layer on the nucleationlayer.
 5. The method of claim 4, wherein the adhesion layer comprises ametal.
 6. The method of claim 4, wherein the adhesion layer comprises ametal nitride.
 7. The method of claim 4, wherein the adhesion layer hasa thickness within a range from about 5 Å to about 25 Å.
 8. The methodof claim 4, wherein the adhesion layer is deposited by atomic layerdeposition or physical vapor deposition.
 9. The method of claim 4,wherein the tungsten nitride intermediate layer has a thickness within arange from about 5 Å to about 150 Å.
 10. The method of claim 4, whereinthe tungsten nitride intermediate layer is deposited by atomic layerdeposition, chemical vapor deposition, or physical vapor deposition. 11.The method of claim 4, wherein the tungsten nitride intermediate layerhas a tungsten concentration within a range from about 40 at % to about60 at %, a nitrogen concentration within a range from about 20 at % toabout 40 at %, and a carbon concentration within a range from about 5 at% to about 15 at %.
 12. The method of claim 4, wherein the tungstennitride intermediate layer has a tungsten concentration within a rangefrom about 40 at % to about 60 at %, a nitrogen concentration within arange from about 5 at % to about 20 at %, and a carbon concentrationwithin a range from about 20 at % to about 40 at %.
 13. The method ofclaim 12, wherein the tungsten barrier layer has a tungstenconcentration within a range from about 70 at % to about 99 at %, anitrogen concentration within a range from about 1 ppb to about 10 at %,and a carbon concentration within a range from about 1 at % to about 15at %.
 14. The method of claim 13, wherein the tungsten barrier layer hasan electrical resistivity of less than 200 Ωμ-cm.
 15. The method ofclaim 12, wherein the tungsten nitride intermediate layer furthercomprises oxygen and has an oxygen concentration within a range fromabout 1 at % to about 10 at %.
 16. The method of claim 15, wherein thetungsten barrier layer further comprises oxygen and has an oxygenconcentration within a range from about 1 ppb to about 1 at %.
 17. Amethod for forming a tungsten-containing material on a substrate,comprising: forming an adhesion layer on a dielectric layer disposed ona substrate; forming a tungsten nitride intermediate layer on theadhesion layer, wherein the tungsten nitride intermediate layercomprises tungsten nitride and carbon; forming a tungsten barrier layerfrom the tungsten nitride intermediate layer during a thermal annealingprocess, wherein the tungsten barrier layer comprises metallic tungstenor tungsten-carbon material formed by thermal decomposition of thetungsten nitride intermediate layer; and forming a tungsten bulk layerdirectly on the tungsten barrier layer.
 18. The method of claim 17,wherein the adhesion layer comprises a metal.
 19. The method of claim17, wherein the adhesion layer comprises a metal nitride.